Re: sniff mode

Luiz Augusto von Dentz
2009-08-24T19:26:30Z

Hi Marcel,

On Mon, Aug 24, 2009 at 3:40 PM, Marcel Holtmann<marcel@holtmann.org> wrote=
:
> Hi Luiz,
>
>> It is just me or hci_conn_enter_active_mode will never do what its
>> name suggests. This check will always succeed:
>>
>> =A0 =A0 =A0 if (conn->mode !=3D HCI_CM_SNIFF || !conn->power_save)
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 goto timer;
>
> so conn->power_save is used to disable automatic sniff mode for incoming
> connections. Mainly HID since they manager it by themselves.

Hmm, but this seems to be done for any device regardless of its type.
So for example we start sending/receiving data to a headset it will
triggers hci_conn_enter_active_mode which I thought would exit sniff
mode, right? (yep, I have seem some headset that doesn't leave sniff
mode by their own).

>> But in hci_mode_change_evt whatever mode different than HCI_CM_ACTIVE
>> reset power_save to zero:
>>
>>
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (!test_and_clear_bit(HCI_CONN_MODE_CHANGE=
_PEND, &conn->pend)) {
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (conn->mode =3D=3D HCI_CM=
_ACTIVE)
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 conn->power_=
save =3D 1;
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 else
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 conn->power_=
save =3D 0;
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 }
>
> And again, we are not setting the sniff mode. We disable automatic sniff
> mode feature.

It really seems the opposite, like we were disabling the automatic
active mode since this make us to always hit goto timer; while in
sniff mode. Perhaps this is meant for when remote device has been
controlling modes, which sound strange to me since hci_mode_change_evt
is called even when the we actively change the mode, right?
(hci_conn_idle does that)

--=20
Luiz Augusto von Dentz
Engenheiro de Computa=E7=E3o